ABSTRACT
Background Exposure to heavy metals has potential adverse impacts on human health, and the concentration of heavy metals in abandoned mining areas may still be higher than that in general areas, so the health risk assessment in such areas cannot be ignored. Objective To explore the health risk of heavy metal exposure and the spatial distribution characteristics of associated main metals in a typical abandoned mining area. Methods Environmental samples of irrigated soil, rice, and drinking water were collected from 13 natural villages under the jurisdiction of a township in Liuzhou, Guangxi from November to December 2019, where a typical abandoned mining was located. Finally, 13 irrigation soil samples, 11 rice samples, and 13 drinking water samples were collected. The concentrations of six metals and metalloid elements in each environmental sample were detected by inductively coupled-plasma mass spectrometry (ICP-MS), including cadmium (Cd), arsenic (As), lead (Pb), chromium (Cr), copper (Cu), and zinc (Zn). At the same time, 251 local residents were recruited for health risk assessment. Model parameters such as body weight, rice intake, and drinking water intake of local residents were obtained through field survey, and the median metal concentration of each environmental sample was taken as the risk assessment parameter of the region. The health risk of heavy metal exposure of local residents was assessed by using oral health risk assessment model of U.S. Environmental Protection Agency. The spatial distribution characteristics of health risks associated with heavy metals were evaluated by empirical Bayes interpolation method using Geographic Information System (GIS) technology. Results The positive rates of Cd, As, Pb, Cr, Cu, and Zn in the irrigated soil samples were 100.00%. The positive rate of Pb was 63.64% in the rice samples, while the rates of other metals were 100.00%. The positive rates of Cd, As, Pb, Cr, Cu, and Zn in the drinking water samples were 53.85%, 76.92%, 92.31%, 15.38%, 84.62%, and 100.00%, respectively. The results of non-carcinogenic risk assessment of oral exposure to heavy metals suggested that the contribution of heavy metals causing non-carcinogenic risk from high to low was As (70.52%) > Cd (18.03%) > Zn (6.63%) > Cu (4.12%) > Pb (0.64%) > Cr (0.06%), and the corresponding estimated non-carcinogenic risk values were 3.54 × 100, 9.05 × 10−1, 3.33 × 10−1, 2.07 × 10−1, 3.23 × 10−2, and 5.42 × 10−4, respectively. The results of carcinogenic risk assessment of oral exposure to heavy metals suggested that the contribution of studied metals from high to low was Cd (87.00%) > As (10.24%) > Cr (2.60%) > Pb (0.16%), and the estimated carcinogenic risks were 4.35× 10−3, 5.12 × 10−4, 1.30 × 10−4, and 3.08 × 10−7, respectively. Rice was the leading media associated with non-carcinogenic risk and carcinogenic risk (99.4% and 99.8% respectively). The spatial distribution characteristics of GIS showed no obvious regularity in the distribution of As in irrigated soil, rice, and drinking water. In rice and irrigated soil, the content of Cd in the villages adjacent to the mining area was obviously higher than that in the other villages, while in drinking water, the content in the villages far away from the mining area was higher. Conclusion As and Cd are the main heavy metals that increase the health risk of local residents in a typical abandoned mining area, and the distribution characteristics of the two heavy metals in different environmental media are not completely consistent.
ABSTRACT
Background Heavy metal pollution in cultivated land will affect crop yield and quality, as well as groundwater quality, ecological security, and human health. Objective To analyze the pollution status of heavy metal elements such as chromium (Cr), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), and lead (Pb) in cultivated soils of the Donghe River Basin in Chenzhou City, and to evaluate the environmental quality of local cultivated soil. Methods A total of 16 samples of cultivated soil from the Donghe River Basin in Chenzhou City were collected, and the contents of Cr, Cu, Zn, As, Cd, and Pb in the samples were determined by inductively coupled plasma mass spectrometry. The Nemerow comprehensive pollution index method (the evaluation indicators included both Nemerow comprehensive pollution index and single pollution index), the geological accumulation index method, and the potential ecological risk index method were used to evaluate the soil environmental quality. Results The average levels of Cr, Cu, Zn, As, Cd, and Pb in the soil samples in the study area were 58.25, 49.50, 273.88, 137.76, 2.92, and 672.29 mg·kg−1, respectively. The average values of Cu, Zn, As, Cd, and Pb were all exceeded the background values of soil elements in Hunan Province. The single pollution indices of As, Cd, Pb, and Zn in soil were 4.40, 9.74, 5.85, and 1.15 respectively. The contamination of As and Pb reached 93.75% and 81.25% respectively. The geological accumulation indices of soil As, Cd, Pb, and Zn were 2.11, 3.71, 2.97, and 0.58, respectively, which showed heavy Cd pollution, moderate As and Pb pollution, and slight Zn pollution. The potential ecological hazard indices of soil Cr, Cu, Zn, As, Pb, and Cd were 1.63, 9.07, 2.90, 87.75, 113.18, and 695.76. 81.Twenty five percent of Cd samples showed heavy pollution and above, and 62.50% of Pb samples had moderate pollution and above. The Nemerow comprehensive pollution index was 7.72, which belonged to heavy pollution; and the comprehensive potential ecological risk index was 910.29, which belonged to high ecological risk. Conclusion There are certain differences in the results of different evaluation methods. The cultivated soils of the Donghe River Basin in Chenzhou City, is seriously polluted by heavy metals, and Cd, As, and Pb are the main polluting elements.
ABSTRACT
Objective To know the environmental lead pollution status of rural areas around the mining area in Guangxi,2008.Methods From August to December,2008,the survey was carried out in 28 villages of 4 counties,which were located in basin of three rivers and their tributaries.Six lead-zinc-tin mines were situated in the investigated area.The local samples were collected,including 101 rice samples,30 paddy samples,59 vegetable samples and 45 samples of meat,viscera of poultry,5 fish samples,and 27 surface water samples,12 ground water samples,13 drinking water samples,29 cropland soil samples.The lead content of them were determined,the dietary survey on lead intake was performed among the residents living near the mining area also.Results 53.68%(102/190) of the crop samples revealed higher lead contents,which were over the standard limit,especially for rice(47.52%) and leafy vegetables(100%).The lead contents for five eggs samples,two peanuts samples and thirteen fresh corns were qualified.36%(102/190)of the samples of meat and viscera of poultry revealed higher lead contents,which were over the standard limit,especially for liver and chicken intestine.The lead intake only through rice and vegetables reached 4.55 mg in one week,which was over the tolerance dose by 0.52 times.Conclusion The lead intake of the residents living near the lead-zinc mining area are mainly from crop and vegetables and poultry.Environmental lead pollution is serious in the investigated area and must be controlled as possible as early.